The HAL Manual (Identification, Analysis, and Correction of High-Crash Locations) was re-titled S-HAL (Safety Handbook for Locals). The First Edition of the HAL Manual was published in 1975. The S-HAL allows local, non-MoDOT agencies to
- Develop a traffic record system (Chap 2)
- Perform network screening (Chap 3)
- Using safety analysis tools (Chap 4)
- Implementing safety improvements (Chap 5)
- Conduct road safety audits (Chap 6) and
- Additional resources (Chap 7).
While the S-HAL was intended for local agencies and law enforcement, it can be a tool for MoDOT personnel as well. The S-HAL is not MoDOT policy, but only a supplemental document to the Engineering Policy Guide (EPG). Any information in the S-HAL that relates to topics in the EPG, the EPG takes precedence.
|MoDOT’s safety engineers constantly search for the best practices in the field to improve Missouri roadways’ safety.
MoDOT has developed a traffic record system focused on the state maintained roadways and is developing the non-state maintained system. MoDOT’s traffic record system is also called the Transportation Management System (TMS). The TMS system uses roadway and crash information to develop High Severity lists for intersections and ranges. Districts are responsible to review these lists to develop their safety program strategies.
While performing network screening on a roadway system, Chapter 3 of the S-HAL explains some of the types of crash rates used when comparing locations. When comparing locations for a safety analysis, crashes are typically normalized by rate. Some of the rates covered by the S-HAL that are used in MoDOT studies include:
- Number of crashes
- Crash severity (EPDO – Equivalent Property Damage Only)
- Crash rate
- Severity Rate (EPDO by rate)
Once potential problem locations are identified, Chapter 4 of the S-HAL recommends information to gather to complete a traffic study. The procedure outlined in the S-HAL can be applied to any request for a field study. The first recommendation is to review crashes and complete a collision diagram. A collision diagram (S-HAL, Figure 4-1) is a spot map that shows where crashes are occurring, either within the intersection or along the range. The collision diagram will show the vehicle action, angle of collision and general location of the crash compared to the roadway. Other information important to the crash is included such as date, time of day, roadway/weather conditions, crash severity, etc. The TMS Accident Browser application uses computer software to produce an automated collision diagram for a single intersection. The collision diagram aids in identifying the predominant crash pattern at that location.
Another process in a traffic study is to perform an on-site observation. Depending on the crash history, it may be important to perform the observation both during the day and at night. The location should be driven from each direction. If there is a possibility for pedestrian travel, the location should be walked in order to view the road, as a pedestrian would experience it. The on-site report (S-HAL, Figure 4-2) should identify the location of the observation points, identify potential hazards by making a physical checklist, make notations regarding pedestrian and driver activity, take photos and interview local people for their observations of the location. When evaluating potential locations, it is important to draw a condition diagram (S-HAL, Figure 4-3), a drawing (to scale, if practical), of the existing roadway, control device locations and major features in the nearby environment. The condition diagram may also include physical road conditions, signing, striping, etc. that may be important in determining a countermeasure analysis. Also included when performing a field observation are traffic counts, spot speed studies and sight distance evaluations. The S-HAL has included worksheets to assist in the development of the location analysis (S-HAL, Figure 4-4).
A Highway Safety Manual analysis should be completed when evaluating safety needs and this analysis is better described in Chapter 4. Tables 4.4 through 4.10 are example worksheets relating to the inputs required for Highway Safety Manual analysis.
According to Chapter 5 of S-HAL, after the locations have been identified, crashes analyzed and field data gathered, the corrective actions are determined. With most locations, there are potential low cost solutions, medium cost solutions, and high cost solutions.